Luego, Josephine N. Department of Environment and Natural Resources, Bureau of Mines Building, Banilad, Mandaue City, 6014 Philippines.

EVALUATION OF TWELVE LEUCAENA SPECIES FOR PSYLLID (H ETERO PSYLLA CUBANA CRAWFORD) RESISTANCE

Introduction and methods. Twelve leucaena cultivars were evaluated in the nursery for resistance to the leucaena psyllid (Heteropsylla cubana Crawford) under Cebu, Philippines conditions. This study formed part of the International Leucaena Research Trial (LPT) network. Cultivars tested were K376, K784, K743, K636, K527, K8, K785, K500, K614, KX1, KX2, and Local Entry of L. leucocephala (Table 1). Seed was obtained from the Nitrogen Fixing Tree Association (Waimanalo, Hawaii). Seven were replicated using simple randomized complete block design (RCBD). The other five entries were unreplicated and served as observational references. Only data from the seven replicated cultivars are presented. Nursery site data are listed in Table 2. Standard psyllid damage rating scales and psyllid egg, nymph, and adult count scales were followed (Wheeler 1988) to evaluate psyllid damage.

Table 1. NFTA leucaena psyllid trial entries.

Species K number OriginReplicated plots

L. pallida K376 Oaxaca, MexicoL. diversifolia K156 Veracruz, MexicoL. diversifolia K784 Veracruz, MexicoL. leucocephala x L. diversifolia K743 (K8 x K156) F2L. leucocephala K636 Coahuila, MexicoL. leucocephala K527 Quintana Roo, MexicoL. leucocephala (control) K8 Zacatecas, Mexico

Unreplicated plotsL. diversifolia K785 Veracruz, MexicoL. leucocephala K500 Australia, CV CunninghamL. leucocephala K614 Tamaulipas, MexicoL . diversifolia x L. pallida KX1 (K156 x K376) F2L. leucocephala x L. pallida KX2 (K636 x K376) F2Local entry " Philippines

Table 2. Site data.

LPT trial number 87-06

Trial location Kilat sub-nursery, CCRP, Buhisan, Cebu CityLatitude 10° 19’ 19.61"Longitude 123° 51’ 29.33"Topography (slope aspect) A ridge with 27.7% slopeElevation 30 mMean annual rainfall 1,628 mmMean annual temperature 28.1° CSoil pH 5 - 6.9Soil texture Silty clay

Results. There was no significant difference between Rhizobium treated and untreated (control) seedlings against psyllid infestation under nursery conditions. Rhizobium may increase seedling growth but inoculation had no effect on leucaena’s reaction to psyllid infestation. Psyllid population count ratings show that K376, K784 and K156 maintained low population level of eggs, nymphs, and adults throughout the experimental period as compared to the hybrid K743 andL. leucocephala cultivars (Tables 4-6). Entries K376, K156 and K784 gave the lowest psyllid damage ratings throughout the study time while K743 showed a reaction similar to that of the L. leucocephala cultivars whose rating ranges from branch tip and leaf curling and yellowing to 100% loss of leaves and blackening of lower leaves (Table 7).

Results of growth performance, fodder and wood yield show that K376, K784 and K156 were outstanding trees for growth and yield (Table 3). They also exhibit good vigor. K636 and K527 are considered psyllid susceptible species yet produced similar biomass as the more psyllid resistant cultivars. K636 and K527 wee able to recover quickly following defoliation and were also able to retain mature leaves which are not attractive to the psyllid.

Correlation between psyllid egg, nymph, adult counts, and psyllid damage showed high positive linear relationships among variables (Table 8). Egg population influenced the number of nymphs, adults, and subsequent damage count. Results indicate that adult counts influenced damage more than nymph counts which could be attributed to an incomplete development of nymphs into adults because of resistant characteristics of the plants, presence of parasites and predators, as well as variations in climatic conditions. Increases in adult populations without complimentary increases in nymphs could be attributed to migration of psyllid adults onto experimental plants from nearly areas.

Conclusions. Of the seven replicated leucaena varieties, Leucaena pallida K376, Leucaena diversifolia K784 and Leucaena diversifolia K156 showed general resistance to the leucaena psyllid and yielded high amounts of wood and fodder under Cebu conditions. Susceptible L. leucocephala species K636 and K527 displayed performances similar to the more resistant species in growth and yield. Leucaena shoot damage was found to be greatly influenced by psyllid adult population.

The leucaenas K376, K784, and K156 are promising substitutes for the "giant ipil-ipil" that was devastated in the region. However, pilot plantations and maintenance of these species should be done first in other provinces in the region to test their stability over time and environmental types. 1

Table 3. Growth measurements and fresh weight biomass yield at seven months of age.1

Treatment Height**Basal**

diameterFresh weight

Leaves* Wood*

K8 (control) 67.7 d 0.8d 170.3 c 0 cK527 75.2 d 0.9d 50.0 c 6.7 cK636 164.8 abc 1.8abc 893.3 a 750.0 abK743 100.7 cd l.lcd 171.0 c 120.3 beK156 142.2 bed 1.5abcd 400.7 abc 400.0 abcK376 217.5 a 1.9a 583.3 abc 1100.0 a

1 Biomass yield taken from 2 m hedge section in each replication. Figures followed by a common letter are not significantly different.

* Significant at 5% level. ** Significant at 1% level.

Table 4. Monthly variations in psyllid egg count from seven leucaena entries.Treatment

Oct** Nov** Dec nsMean Psyllid egg count rating1

Mar* Apr** May™ Jun** Jul** Aug** Sep**K8 2.3c 3.7bcd 2.3 2.6a 4.6ab 1.3 2.7ab 7.6abc 5.9a 5.3aK527 7.3ab 5.0bcd 4.0 2.5ab 3.8abc 1.0 2.8 8.4a 4.2abc 3.6bcK636 7.7a 6.7a 2.3 2.7a 4.9a 1.0 1.8c 7.0abcd 4.0bcd 3.7bK743 4.7abc 4:3abc 4.0 2.6a 3.2cd 1.0 1.1c 7.7ab 4.5ab 2.9bcdK784 2.7c 2.3cd 3.0 1.0b 2.4cd 1.0 1.0c 3.5e 2.0e 2.0dK156 3.7c 2.7bcd 3.7 1.0b 3.led 1.0 1.0c 5.6bcde 3.0bcde 2.5bcdK376 1.7c 1.7d 2.7 1.0b 1.9d 1.0 1.0c 4.4e 2.0e 2.6d

Table 5. Monthly variations in psyllid nymph count from seven leucaena entries.Treatment

Oct** Nov** Dec nsMean Psyllid nymph count rating1

Mar* Apr** May™ Jun** Jul** Aug** Sep**K8 3.7cde 9.0a 9.0 1.4 3.4a 1.0 1.7ab 7.4abcd 6.2a 5.5aK527 6.0abcd 8.0abc 9.0 1.1 2.8a 1.0 1.8a 8.5a 4.6ab 4.0bcK636 9.0a 9.0ab 9.0 1.5 2.9a 1.0 1.0c 7.4abc 4.led 4.5abK743 8.7ab 7.0abcd 9.0 1.9 2.6a 1.0 1.0c 7.4ab 4.3abc 3.3bcK784 5.0cde 7.0abcde 8.7 1.0 2.1bc 1.0 1.0c 3.7e 2.0e 2.0dK156 7.0abc 6.7abcde 9.0 1.0 2.5ab 1.0 1.0c 5.9abcd 2.9bcd 2.9bcdK376 1.7e _iZs__ 5.3 1.0 1.7c 1.0 1.0c 3.7e 2.0e 2.0d

Table 6. Monthly variations in psyllid adult count from seven leucaena entries.Treatment

Oct** Nov** Dec nsMean Psyllid adult count rating1

Mar* Apr** May™ Jun** Jul** Aug** Sep**K8 4.0 2.7 2.3 1.8 2.6 1.0 1.7ab 7.3 abed 6.2a 5.6aK527 3.3 2.7 3.0 1.5 2.7 1.0 1.8a 8.5a 4.7abc 4.1abcK636 4.3 3.7 2.3 1.9 2.5 1.0 1.0c 7.4abc 4.2ab 4.5abK743 3.7 2.0 4.0 1.7 2.6 1.0 1.2bc 7.6ab 4.4abcd 3.4bcdK784 1.7 1.3 3.0 1.0 2.1 1.0 1.0c 3.7e 2.0e 2.0dK156 2.3 3.7 3.7 1.1 2.5 1.0 1.0c 6.1abcde 2.9bcde 2.9bcdK376 1.3 2.3 1.0 1.7 1.0 1.0c 3.7e 2.0e 2.0d

Table 7. Monthly variation in damage rating caused by the psyllid.Treatment

Oct** Nov** Dec nsMean Pallid damage rating1

Mar* Apr** May™ Jun** Jul** Aug** Sep**K8 3.5a 3.5a 3.8a 4.2abc 4.6ab 1.6 1.5ab 7.7ab 5.6a 5.5aK527 3.lab 3.2ab 3.8ab 3.7abcd 3.7abc 1.5 2.0a 8.2a 4.3 3.8abK636 3.0abc 3.0abc 3.4abcd 4.3ab 4.2a 1.4 1.4bc 6.9abc 3.9abcd 3.6abcK743 3.0abcd 2.7abcd 3.6abc 4.6a 3.3abcd 1.1 l.lab 6.5abcd 3.9abcd 2.4bcdK784 1.5ef 1.7ef 1.9f l.Oe 2.0cde 1.0 1.0c 3.2e 1.4e 1.2dK156 2.5abcde 2.3bcde 2.9e l.Oe 2.5abcd 1.0 1.0c 4.7cde 2.6bcde 1.7bcdK376 1.3f 1.2f 1-lg l.Oe 1.3e 1.0 1.0c 3.1e 1.2e l.Od

1 Means followed by a common letter are not significantly different from each other, ns = not significant; * = significant at 5% level; ** = significant at 1 % level.

Table 8. Correlation coefficient among variables.1

Egg count Nymph count Adult count Damage countEgg count 1.000 0.696 0.839 0.812Nymph count 0.696 1.000 0.623 0.536Adult count 0.839 0.623 1.000 0.850Damage count 0.812 0.536 0.850 1.0001 R values are highly significant at 1% level.

References:

Bray, R A . and T.D. Woodroffe. 1988. Some observation on the population dynamics of the Leucaena psyllid in southeast Queensland. Leucaena Res. Reports 9:8-10.

Glover, N. 1988. Evaluation of Leucaena species for psyllid resistance. Leucaena Res. Reports 9:15-18.

McFadden, M.W. 1986. Evaluation of the Leucaena/ Heteropsylla problem in Hawaii, in the Philippines and New Caledonia. Forest Insect and Disease Research, USDA Forest Service, Washington, D.C. Forest Support Program.

Sorensson, C.T. and J.L. Brewbaker. 1984. Newly introduced psyllid in Hawaii injurious to Leucaena. Leucaena Res. Reports 5:91-93.

Whe’eler, R A . 1988. Leucaena psyllid trial at Waimanalo, Hawaii. Leucaena Res. Reports 9:25- 29.